Automatic fingerprint scanners are commonly used to obtain an analog or digital image for security, access, verification, or record-keeping applications. In most conventional scanners, a two-dimensional (2D) image of the fingerprint is captured by an imaging device having a matrix of picture elements or pixels arranged as multiple rows and columns. A 2D light-sensitive electronic sensor, such as a charge-coupled device (CCD), is typically used to capture a fingerprint image. However, the cost, size, and uniformity requirements of traditional lighting sources may make them expensive or impractical for use in some constrained physical environments, such as keyboards, laptop computers, and pointing devices such as a mouse or trackball.
A traditional method of illuminating a fingerprint in an imaging device is to use a light source positioned below a transparent platen of the device. However, this method typically increases the cost and size of the imaging device and may not provide uniform illumination of the fingerprint or background of the fingerprint image.
Therefore, there is a need for a small and inexpensive way of illuminating a fingerprint in a constrained physical environment.